Supplementary Material for: Exome Sequencing Identification of <b><i>EP300</i></b> Mutation in a Proband with Coloboma and Imperforate Anus: Possible Expansion of the Phenotypic Spectrum of Rubinstein-Taybi Syndrome

Rubinstein-Taybi syndrome (RSTS) is a multisystem developmental disorder characterized by facial dysmorphisms, broad thumbs and halluces, growth retardation, and intellectual disability. In about 8% of RSTS cases, mutations are found in <i>EP300</i>. Previously, the <i>EP300</i> mutation has been shown to cause the highly variable RSTS phenotype. Using exome sequencing, we identified a de novo <i>EP300</i> frameshift mutation in a proband with coloboma, facial asymmetry and imperforate anus with minimal RSTS features. Previous molecular studies have demonstrated the importance of EP300 in oculogenesis, supporting the possibility that <i>EP300</i> mutation may cause ocular coloboma. Since a wide phenotypic spectrum is well known in <i>EP300</i>-associated RSTS cases, the atypical phenotype identified in our proband may be an example of rare manifestations of RSTS.